1 \input texinfo @c -*- texinfo -*-
3 @settitle avconv Documentation
5 @center @titlefont{avconv Documentation}
14 The generic syntax is:
18 avconv [global options] [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}...
23 @c man begin DESCRIPTION
25 avconv is a very fast video and audio converter that can also grab from
26 a live audio/video source. It can also convert between arbitrary sample
27 rates and resize video on the fly with a high quality polyphase filter.
29 avconv reads from an arbitrary number of input "files" (which can be regular
30 files, pipes, network streams, grabbing devices, etc.), specified by the
31 @code{-i} option, and writes to an arbitrary number of output "files", which are
32 specified by a plain output filename. Anything found on the command line which
33 cannot be interpreted as an option is considered to be an output filename.
35 Each input or output file can in principle contain any number of streams of
36 different types (video/audio/subtitle/attachment/data). Allowed number and/or
37 types of streams can be limited by the container format. Selecting, which
38 streams from which inputs go into output, is done either automatically or with
39 the @code{-map} option (see the Stream selection chapter).
41 To refer to input files in options, you must use their indices (0-based). E.g.
42 the first input file is @code{0}, the second is @code{1} etc. Similarly, streams
43 within a file are referred to by their indices. E.g. @code{2:3} refers to the
44 fourth stream in the third input file. See also the Stream specifiers chapter.
46 As a general rule, options are applied to the next specified
47 file. Therefore, order is important, and you can have the same
48 option on the command line multiple times. Each occurrence is
49 then applied to the next input or output file.
50 Exceptions from this rule are the global options (e.g. verbosity level),
51 which should be specified first.
53 Do not mix input and output files -- first specify all input files, then all
54 output files. Also do not mix options which belong to different files. All
55 options apply ONLY to the next input or output file and are reset between files.
59 To set the video bitrate of the output file to 64kbit/s:
61 avconv -i input.avi -b 64k output.avi
65 To force the frame rate of the output file to 24 fps:
67 avconv -i input.avi -r 24 output.avi
71 To force the frame rate of the input file (valid for raw formats only)
72 to 1 fps and the frame rate of the output file to 24 fps:
74 avconv -r 1 -i input.m2v -r 24 output.avi
78 The format option may be needed for raw input files.
80 @c man end DESCRIPTION
82 @chapter Detailed description
83 @c man begin DETAILED DESCRIPTION
85 The transcoding process in @command{avconv} for each output can be described by
86 the following diagram:
89 _______ ______________
91 | input | demuxer | encoded data | decoder
92 | file | ---------> | packets | -----+
93 |_______| |______________| |
100 ________ ______________ |
102 | output | <-------- | encoded data | <----+
103 | file | muxer | packets | encoder
104 |________| |______________|
109 @command{avconv} calls the libavformat library (containing demuxers) to read
110 input files and get packets containing encoded data from them. When there are
111 multiple input files, @command{avconv} tries to keep them synchronized by
112 tracking lowest timestamp on any active input stream.
114 Encoded packets are then passed to the decoder (unless streamcopy is selected
115 for the stream, see further for a description). The decoder produces
116 uncompressed frames (raw video/PCM audio/...) which can be processed further by
117 filtering (see next section). After filtering the frames are passed to the
118 encoder, which encodes them and outputs encoded packets again. Finally those are
119 passed to the muxer, which writes the encoded packets to the output file.
122 Before encoding, @command{avconv} can process raw audio and video frames using
123 filters from the libavfilter library. Several chained filters form a filter
124 graph. @command{avconv} distinguishes between two types of filtergraphs -
127 @subsection Simple filtergraphs
128 Simple filtergraphs are those that have exactly one input and output, both of
129 the same type. In the above diagram they can be represented by simply inserting
130 an additional step between decoding and encoding:
133 _________ ______________
135 | decoded | | encoded data |
136 | frames |\ /| packets |
137 |_________| \ / |______________|
139 simple \ | | / encoder
140 filtergraph \| filtered |/
146 Simple filtergraphs are configured with the per-stream @option{-filter} option
147 (with @option{-vf} and @option{-af} aliases for video and audio respectively).
148 A simple filtergraph for video can look for example like this:
151 _______ _____________ _______ ________
153 | input | ---> | deinterlace | ---> | scale | ---> | output |
154 |_______| |_____________| |_______| |________|
158 Note that some filters change frame properties but not frame contents. E.g. the
159 @code{fps} filter in the example above changes number of frames, but does not
160 touch the frame contents. Another example is the @code{setpts} filter, which
161 only sets timestamps and otherwise passes the frames unchanged.
163 @subsection Complex filtergraphs
164 Complex filtergraphs are those which cannot be described as simply a linear
165 processing chain applied to one stream. This is the case e.g. when the graph has
166 more than one input and/or output, or when output stream type is different from
167 input. They can be represented with the following diagram:
172 | input 0 |\ __________
174 \ _________ /| output 0 |
176 _________ \| complex | /
178 | input 1 |---->| filter |\
179 |_________| | | \ __________
182 _________ / |_________| |__________|
189 Complex filtergraphs are configured with the @option{-filter_complex} option.
190 Note that this option is global, since a complex filtergraph by its nature
191 cannot be unambiguously associated with a single stream or file.
193 A trivial example of a complex filtergraph is the @code{overlay} filter, which
194 has two video inputs and one video output, containing one video overlaid on top
195 of the other. Its audio counterpart is the @code{amix} filter.
198 Stream copy is a mode selected by supplying the @code{copy} parameter to the
199 @option{-codec} option. It makes @command{avconv} omit the decoding and encoding
200 step for the specified stream, so it does only demuxing and muxing. It is useful
201 for changing the container format or modifying container-level metadata. The
202 diagram above will in this case simplify to this:
205 _______ ______________ ________
207 | input | demuxer | encoded data | muxer | output |
208 | file | ---------> | packets | -------> | file |
209 |_______| |______________| |________|
213 Since there is no decoding or encoding, it is very fast and there is no quality
214 loss. However it might not work in some cases because of many factors. Applying
215 filters is obviously also impossible, since filters work on uncompressed data.
217 @c man end DETAILED DESCRIPTION
219 @chapter Stream selection
220 @c man begin STREAM SELECTION
222 By default avconv tries to pick the "best" stream of each type present in input
223 files and add them to each output file. For video, this means the highest
224 resolution, for audio the highest channel count. For subtitle it's simply the
225 first subtitle stream.
227 You can disable some of those defaults by using @code{-vn/-an/-sn} options. For
228 full manual control, use the @code{-map} option, which disables the defaults just
231 @c man end STREAM SELECTION
236 @include avtools-common-opts.texi
238 @section Main options
242 @item -f @var{fmt} (@emph{input/output})
243 Force input or output file format. The format is normally autodetected for input
244 files and guessed from file extension for output files, so this option is not
245 needed in most cases.
247 @item -i @var{filename} (@emph{input})
250 @item -y (@emph{global})
251 Overwrite output files without asking.
253 @item -n (@emph{global})
254 Immediately exit when output files already exist.
256 @item -loop @var{number} (@emph{input})
257 Set number of times input stream shall be looped. Loop 0 means no loop,
258 loop -1 means infinite loop.
260 @item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
261 @itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
262 Select an encoder (when used before an output file) or a decoder (when used
263 before an input file) for one or more streams. @var{codec} is the name of a
264 decoder/encoder or a special value @code{copy} (output only) to indicate that
265 the stream is not to be reencoded.
269 avconv -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
271 encodes all video streams with libx264 and copies all audio streams.
273 For each stream, the last matching @code{c} option is applied, so
275 avconv -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
277 will copy all the streams except the second video, which will be encoded with
278 libx264, and the 138th audio, which will be encoded with libvorbis.
280 @item -t @var{duration} (@emph{output})
281 Stop writing the output after its duration reaches @var{duration}.
282 @var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
284 @item -fs @var{limit_size} (@emph{output})
285 Set the file size limit.
287 @item -ss @var{position} (@emph{input/output})
288 When used as an input option (before @code{-i}), seeks in this input file to
289 @var{position}. Note the in most formats it is not possible to seek exactly, so
290 @command{avconv} will seek to the closest seek point before @var{position}.
291 When transcoding and @option{-accurate_seek} is enabled (the default), this
292 extra segment between the seek point and @var{position} will be decoded and
293 discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it
296 When used as an output option (before an output filename), decodes but discards
297 input until the timestamps reach @var{position}.
299 @var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.
301 @item -itsoffset @var{offset} (@emph{input})
302 Set the input time offset in seconds.
303 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
304 The offset is added to the timestamps of the input files.
305 Specifying a positive offset means that the corresponding
306 streams are delayed by @var{offset} seconds.
308 @item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
309 Set a metadata key/value pair.
311 An optional @var{metadata_specifier} may be given to set metadata
312 on streams or chapters. See @code{-map_metadata} documentation for
315 This option overrides metadata set with @code{-map_metadata}. It is
316 also possible to delete metadata by using an empty value.
318 For example, for setting the title in the output file:
320 avconv -i in.avi -metadata title="my title" out.flv
323 To set the language of the first audio stream:
325 avconv -i INPUT -metadata:s:a:0 language=eng OUTPUT
328 @item -target @var{type} (@emph{output})
329 Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
330 @code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
331 @code{film-} to use the corresponding standard. All the format options
332 (bitrate, codecs, buffer sizes) are then set automatically. You can just type:
335 avconv -i myfile.avi -target vcd /tmp/vcd.mpg
338 Nevertheless you can specify additional options as long as you know
339 they do not conflict with the standard, as in:
342 avconv -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
345 @item -dframes @var{number} (@emph{output})
346 Set the number of data frames to record. This is an obsolete alias for
347 @code{-frames:d}, which you should use instead.
349 @item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
350 Stop writing to the stream after @var{framecount} frames.
352 @item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
353 @itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
354 Use fixed quality scale (VBR). The meaning of @var{q} is
357 @item -filter[:@var{stream_specifier}] @var{filter_graph} (@emph{output,per-stream})
358 @var{filter_graph} is a description of the filter graph to apply to
359 the stream. Use @code{-filters} to show all the available filters
360 (including also sources and sinks).
362 See also the @option{-filter_complex} option if you want to create filter graphs
363 with multiple inputs and/or outputs.
365 @item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream})
366 This option is similar to @option{-filter}, the only difference is that its
367 argument is the name of the file from which a filtergraph description is to be
370 @item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
371 Specify the preset for matching stream(s).
373 @item -stats (@emph{global})
374 Print encoding progress/statistics. On by default.
376 @item -attach @var{filename} (@emph{output})
377 Add an attachment to the output file. This is supported by a few formats
378 like Matroska for e.g. fonts used in rendering subtitles. Attachments
379 are implemented as a specific type of stream, so this option will add
380 a new stream to the file. It is then possible to use per-stream options
381 on this stream in the usual way. Attachment streams created with this
382 option will be created after all the other streams (i.e. those created
383 with @code{-map} or automatic mappings).
385 Note that for Matroska you also have to set the mimetype metadata tag:
387 avconv -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
389 (assuming that the attachment stream will be third in the output file).
391 @item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
392 Extract the matching attachment stream into a file named @var{filename}. If
393 @var{filename} is empty, then the value of the @code{filename} metadata tag
396 E.g. to extract the first attachment to a file named 'out.ttf':
398 avconv -dump_attachment:t:0 out.ttf INPUT
400 To extract all attachments to files determined by the @code{filename} tag:
402 avconv -dump_attachment:t "" INPUT
405 Technical note -- attachments are implemented as codec extradata, so this
406 option can actually be used to extract extradata from any stream, not just
410 Disable automatically rotating video based on file metadata.
414 @section Video Options
417 @item -vframes @var{number} (@emph{output})
418 Set the number of video frames to record. This is an obsolete alias for
419 @code{-frames:v}, which you should use instead.
420 @item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
421 Set frame rate (Hz value, fraction or abbreviation).
423 As an input option, ignore any timestamps stored in the file and instead
424 generate timestamps assuming constant frame rate @var{fps}.
426 As an output option, duplicate or drop input frames to achieve constant output
427 frame rate @var{fps} (note that this actually causes the @code{fps} filter to be
428 inserted to the end of the corresponding filtergraph).
430 @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
433 As an input option, this is a shortcut for the @option{video_size} private
434 option, recognized by some demuxers for which the frame size is either not
435 stored in the file or is configurable -- e.g. raw video or video grabbers.
437 As an output option, this inserts the @code{scale} video filter to the
438 @emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
439 directly to insert it at the beginning or some other place.
441 The format is @samp{wxh} (default - same as source). The following
442 abbreviations are recognized:
512 @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
513 Set the video display aspect ratio specified by @var{aspect}.
515 @var{aspect} can be a floating point number string, or a string of the
516 form @var{num}:@var{den}, where @var{num} and @var{den} are the
517 numerator and denominator of the aspect ratio. For example "4:3",
518 "16:9", "1.3333", and "1.7777" are valid argument values.
520 @item -vn (@emph{output})
521 Disable video recording.
523 @item -vcodec @var{codec} (@emph{output})
524 Set the video codec. This is an alias for @code{-codec:v}.
526 @item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
527 Select the pass number (1 or 2). It is used to do two-pass
528 video encoding. The statistics of the video are recorded in the first
529 pass into a log file (see also the option -passlogfile),
530 and in the second pass that log file is used to generate the video
531 at the exact requested bitrate.
532 On pass 1, you may just deactivate audio and set output to null,
533 examples for Windows and Unix:
535 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
536 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
539 @item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
540 Set two-pass log file name prefix to @var{prefix}, the default file name
541 prefix is ``av2pass''. The complete file name will be
542 @file{PREFIX-N.log}, where N is a number specific to the output
545 @item -vf @var{filter_graph} (@emph{output})
546 @var{filter_graph} is a description of the filter graph to apply to
548 Use the option "-filters" to show all the available filters (including
549 also sources and sinks). This is an alias for @code{-filter:v}.
553 @section Advanced Video Options
556 @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
557 Set pixel format. Use @code{-pix_fmts} to show all the supported
559 @item -sws_flags @var{flags} (@emph{input/output})
564 @item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
565 rate control override for specific intervals
568 Dump video coding statistics to @file{vstats_HHMMSS.log}.
569 @item -vstats_file @var{file}
570 Dump video coding statistics to @var{file}.
571 @item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
572 top=1/bottom=0/auto=-1 field first
573 @item -dc @var{precision}
575 @item -vtag @var{fourcc/tag} (@emph{output})
576 Force video tag/fourcc. This is an alias for @code{-tag:v}.
577 @item -qphist (@emph{global})
579 @item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
580 Force key frames at the specified timestamps, more precisely at the first
581 frames after each specified time.
582 This option can be useful to ensure that a seek point is present at a
583 chapter mark or any other designated place in the output file.
584 The timestamps must be specified in ascending order.
586 @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
587 When doing stream copy, copy also non-key frames found at the
590 @item -hwaccel[:@var{stream_specifier}] @var{hwaccel} (@emph{input,per-stream})
591 Use hardware acceleration to decode the matching stream(s). The allowed values
592 of @var{hwaccel} are:
595 Do not use any hardware acceleration (the default).
598 Automatically select the hardware acceleration method.
601 Use Apple VDA hardware acceleration.
604 Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
607 Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
610 Use the Intel QuickSync Video acceleration for video transcoding.
612 Unlike most other values, this option does not enable accelerated decoding (that
613 is used automatically whenever a qsv decoder is selected), but accelerated
614 transcoding, without copying the frames into the system memory.
616 For it to work, both the decoder and the encoder must support QSV acceleration
617 and no filters must be used.
620 This option has no effect if the selected hwaccel is not available or not
621 supported by the chosen decoder.
623 Note that most acceleration methods are intended for playback and will not be
624 faster than software decoding on modern CPUs. Additionally, @command{avconv}
625 will usually need to copy the decoded frames from the GPU memory into the system
626 memory, resulting in further performance loss. This option is thus mainly
629 @item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream})
630 Select a device to use for hardware acceleration.
632 This option only makes sense when the @option{-hwaccel} option is also
633 specified. Its exact meaning depends on the specific hardware acceleration
638 For VDPAU, this option specifies the X11 display/screen to use. If this option
639 is not specified, the value of the @var{DISPLAY} environment variable is used
642 For DXVA2, this option should contain the number of the display adapter to use.
643 If this option is not specified, the default adapter is used.
646 For QSV, this option corresponds to the values of MFX_IMPL_* . Allowed values
661 List all hardware acceleration methods supported in this build of avconv.
665 @section Audio Options
668 @item -aframes @var{number} (@emph{output})
669 Set the number of audio frames to record. This is an obsolete alias for
670 @code{-frames:a}, which you should use instead.
671 @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
672 Set the audio sampling frequency. For output streams it is set by
673 default to the frequency of the corresponding input stream. For input
674 streams this option only makes sense for audio grabbing devices and raw
675 demuxers and is mapped to the corresponding demuxer options.
676 @item -aq @var{q} (@emph{output})
677 Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
678 @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
679 Set the number of audio channels. For output streams it is set by
680 default to the number of input audio channels. For input streams
681 this option only makes sense for audio grabbing devices and raw demuxers
682 and is mapped to the corresponding demuxer options.
683 @item -an (@emph{output})
684 Disable audio recording.
685 @item -acodec @var{codec} (@emph{input/output})
686 Set the audio codec. This is an alias for @code{-codec:a}.
687 @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
688 Set the audio sample format. Use @code{-sample_fmts} to get a list
689 of supported sample formats.
690 @item -af @var{filter_graph} (@emph{output})
691 @var{filter_graph} is a description of the filter graph to apply to
693 Use the option "-filters" to show all the available filters (including
694 also sources and sinks). This is an alias for @code{-filter:a}.
697 @section Advanced Audio options:
700 @item -atag @var{fourcc/tag} (@emph{output})
701 Force audio tag/fourcc. This is an alias for @code{-tag:a}.
704 @section Subtitle options:
707 @item -scodec @var{codec} (@emph{input/output})
708 Set the subtitle codec. This is an alias for @code{-codec:s}.
709 @item -sn (@emph{output})
710 Disable subtitle recording.
713 @section Advanced options
716 @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
718 Designate one or more input streams as a source for the output file. Each input
719 stream is identified by the input file index @var{input_file_id} and
720 the input stream index @var{input_stream_id} within the input
721 file. Both indices start at 0. If specified,
722 @var{sync_file_id}:@var{stream_specifier} sets which input stream
723 is used as a presentation sync reference.
725 The first @code{-map} option on the command line specifies the
726 source for output stream 0, the second @code{-map} option specifies
727 the source for output stream 1, etc.
729 A @code{-} character before the stream identifier creates a "negative" mapping.
730 It disables matching streams from already created mappings.
732 An alternative @var{[linklabel]} form will map outputs from complex filter
733 graphs (see the @option{-filter_complex} option) to the output file.
734 @var{linklabel} must correspond to a defined output link label in the graph.
736 For example, to map ALL streams from the first input file to output
738 avconv -i INPUT -map 0 output
741 For example, if you have two audio streams in the first input file,
742 these streams are identified by "0:0" and "0:1". You can use
743 @code{-map} to select which streams to place in an output file. For
746 avconv -i INPUT -map 0:1 out.wav
748 will map the input stream in @file{INPUT} identified by "0:1" to
749 the (single) output stream in @file{out.wav}.
751 For example, to select the stream with index 2 from input file
752 @file{a.mov} (specified by the identifier "0:2"), and stream with
753 index 6 from input @file{b.mov} (specified by the identifier "1:6"),
754 and copy them to the output file @file{out.mov}:
756 avconv -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
759 To select all video and the third audio stream from an input file:
761 avconv -i INPUT -map 0:v -map 0:a:2 OUTPUT
764 To map all the streams except the second audio, use negative mappings
766 avconv -i INPUT -map 0 -map -0:a:1 OUTPUT
769 To pick the English audio stream:
771 avconv -i INPUT -map 0:m:language:eng OUTPUT
774 Note that using this option disables the default mappings for this output file.
776 @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
777 Set metadata information of the next output file from @var{infile}. Note that
778 those are file indices (zero-based), not filenames.
779 Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
780 A metadata specifier can have the following forms:
783 global metadata, i.e. metadata that applies to the whole file
785 @item @var{s}[:@var{stream_spec}]
786 per-stream metadata. @var{stream_spec} is a stream specifier as described
787 in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
788 matching stream is copied from. In an output metadata specifier, all matching
789 streams are copied to.
791 @item @var{c}:@var{chapter_index}
792 per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
794 @item @var{p}:@var{program_index}
795 per-program metadata. @var{program_index} is the zero-based program index.
797 If metadata specifier is omitted, it defaults to global.
799 By default, global metadata is copied from the first input file,
800 per-stream and per-chapter metadata is copied along with streams/chapters. These
801 default mappings are disabled by creating any mapping of the relevant type. A negative
802 file index can be used to create a dummy mapping that just disables automatic copying.
804 For example to copy metadata from the first stream of the input file to global metadata
807 avconv -i in.ogg -map_metadata 0:s:0 out.mp3
810 To do the reverse, i.e. copy global metadata to all audio streams:
812 avconv -i in.mkv -map_metadata:s:a 0:g out.mkv
814 Note that simple @code{0} would work as well in this example, since global
815 metadata is assumed by default.
817 @item -map_chapters @var{input_file_index} (@emph{output})
818 Copy chapters from input file with index @var{input_file_index} to the next
819 output file. If no chapter mapping is specified, then chapters are copied from
820 the first input file with at least one chapter. Use a negative file index to
821 disable any chapter copying.
823 Print specific debug info.
824 @item -benchmark (@emph{global})
825 Show benchmarking information at the end of an encode.
826 Shows CPU time used and maximum memory consumption.
827 Maximum memory consumption is not supported on all systems,
828 it will usually display as 0 if not supported.
829 @item -timelimit @var{duration} (@emph{global})
830 Exit after avconv has been running for @var{duration} seconds.
831 @item -dump (@emph{global})
832 Dump each input packet to stderr.
833 @item -hex (@emph{global})
834 When dumping packets, also dump the payload.
835 @item -re (@emph{input})
836 Read input at native frame rate. Mainly used to simulate a grab device
837 or live input stream (e.g. when reading from a file). Should not be used
838 with actual grab devices or live input streams (where it can cause packet
840 @item -vsync @var{parameter}
845 Each frame is passed with its timestamp from the demuxer to the muxer.
847 Frames will be duplicated and dropped to achieve exactly the requested
850 Frames are passed through with their timestamp or dropped so as to
851 prevent 2 frames from having the same timestamp.
853 Chooses between 1 and 2 depending on muxer capabilities. This is the
857 With -map you can select from which stream the timestamps should be
858 taken. You can leave either video or audio unchanged and sync the
859 remaining stream(s) to the unchanged one.
861 @item -async @var{samples_per_second}
862 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
863 the parameter is the maximum samples per second by which the audio is changed.
864 -async 1 is a special case where only the start of the audio stream is corrected
865 without any later correction.
866 This option has been deprecated. Use the @code{asyncts} audio filter instead.
868 Copy timestamps from input to output.
870 Copy input stream time base from input to output when stream copying.
871 @item -shortest (@emph{output})
872 Finish encoding when the shortest input stream ends.
873 @item -dts_delta_threshold
874 Timestamp discontinuity delta threshold.
875 @item -muxdelay @var{seconds} (@emph{input})
876 Set the maximum demux-decode delay.
877 @item -muxpreload @var{seconds} (@emph{input})
878 Set the initial demux-decode delay.
879 @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
880 Assign a new stream-id value to an output stream. This option should be
881 specified prior to the output filename to which it applies.
882 For the situation where multiple output files exist, a streamid
883 may be reassigned to a different value.
885 For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
886 an output mpegts file:
888 avconv -i infile -streamid 0:33 -streamid 1:36 out.ts
891 @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
892 Set bitstream filters for matching streams. @var{bitstream_filters} is
893 a comma-separated list of bitstream filters. Use the @code{-bsfs} option
894 to get the list of bitstream filters.
896 avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
899 avconv -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
902 @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{input/output,per-stream})
903 Force a tag/fourcc for matching streams.
905 @item -filter_complex @var{filtergraph} (@emph{global})
906 Define a complex filter graph, i.e. one with arbitrary number of inputs and/or
907 outputs. For simple graphs -- those with one input and one output of the same
908 type -- see the @option{-filter} options. @var{filtergraph} is a description of
909 the filter graph, as described in @ref{Filtergraph syntax}.
911 Input link labels must refer to input streams using the
912 @code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
913 uses). If @var{stream_specifier} matches multiple streams, the first one will be
914 used. An unlabeled input will be connected to the first unused input stream of
917 Output link labels are referred to with @option{-map}. Unlabeled outputs are
918 added to the first output file.
920 Note that with this option it is possible to use only lavfi sources without
923 For example, to overlay an image over video
925 avconv -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
928 Here @code{[0:v]} refers to the first video stream in the first input file,
929 which is linked to the first (main) input of the overlay filter. Similarly the
930 first video stream in the second input is linked to the second (overlay) input
933 Assuming there is only one video stream in each input file, we can omit input
934 labels, so the above is equivalent to
936 avconv -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
940 Furthermore we can omit the output label and the single output from the filter
941 graph will be added to the output file automatically, so we can simply write
943 avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
946 To generate 5 seconds of pure red video using lavfi @code{color} source:
948 avconv -filter_complex 'color=red' -t 5 out.mkv
951 @item -filter_complex_script @var{filename} (@emph{global})
952 This option is similar to @option{-filter_complex}, the only difference is that
953 its argument is the name of the file from which a complex filtergraph
954 description is to be read.
956 @item -accurate_seek (@emph{input})
957 This option enables or disables accurate seeking in input files with the
958 @option{-ss} option. It is enabled by default, so seeking is accurate when
959 transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
960 e.g. when copying some streams and transcoding the others.
962 @item -max_muxing_queue_size @var{packets} (@emph{output,per-stream})
963 When transcoding audio and/or video streams, avconv will not begin writing into
964 the output until it has one packet for each such stream. While waiting for that
965 to happen, packets for other streams are buffered. This option sets the size of
966 this buffer, in packets, for the matching output stream.
968 The default value of this option should be high enough for most uses, so only
969 touch this option if you are sure that you need it.
979 For streaming at very low bitrate application, use a low frame rate
980 and a small GOP size. This is especially true for RealVideo where
981 the Linux player does not seem to be very fast, so it can miss
982 frames. An example is:
985 avconv -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
989 The parameter 'q' which is displayed while encoding is the current
990 quantizer. The value 1 indicates that a very good quality could
991 be achieved. The value 31 indicates the worst quality. If q=31 appears
992 too often, it means that the encoder cannot compress enough to meet
993 your bitrate. You must either increase the bitrate, decrease the
994 frame rate or decrease the frame size.
997 If your computer is not fast enough, you can speed up the
998 compression at the expense of the compression ratio. You can use
999 '-me zero' to speed up motion estimation, and '-g 0' to disable
1000 motion estimation completely (you have only I-frames, which means it
1001 is about as good as JPEG compression).
1004 To have very low audio bitrates, reduce the sampling frequency
1005 (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
1008 To have a constant quality (but a variable bitrate), use the option
1009 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
1016 @c man begin EXAMPLES
1018 @section Preset files
1020 A preset file contains a sequence of @var{option=value} pairs, one for
1021 each line, specifying a sequence of options which can be specified also on
1022 the command line. Lines starting with the hash ('#') character are ignored and
1023 are used to provide comments. Empty lines are also ignored. Check the
1024 @file{presets} directory in the Libav source tree for examples.
1026 Preset files are specified with the @code{pre} option, this option takes a
1027 preset name as input. Avconv searches for a file named @var{preset_name}.avpreset in
1028 the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.avconv}, and in
1029 the data directory defined at configuration time (usually @file{$PREFIX/share/avconv})
1030 in that order. For example, if the argument is @code{libx264-max}, it will
1031 search for the file @file{libx264-max.avpreset}.
1033 @section Video and Audio grabbing
1035 If you specify the input format and device then avconv can grab video
1039 avconv -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
1042 Note that you must activate the right video source and channel before
1043 launching avconv with any TV viewer such as
1044 @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
1045 have to set the audio recording levels correctly with a
1048 @section X11 grabbing
1050 Grab the X11 display with avconv via
1053 avconv -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg
1056 0.0 is display.screen number of your X11 server, same as
1057 the DISPLAY environment variable.
1060 avconv -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg
1063 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
1064 variable. 10 is the x-offset and 20 the y-offset for the grabbing.
1066 @section Video and Audio file format conversion
1068 Any supported file format and protocol can serve as input to avconv:
1073 You can use YUV files as input:
1076 avconv -i /tmp/test%d.Y /tmp/out.mpg
1079 It will use the files:
1081 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
1082 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
1085 The Y files use twice the resolution of the U and V files. They are
1086 raw files, without header. They can be generated by all decent video
1087 decoders. You must specify the size of the image with the @option{-s} option
1088 if avconv cannot guess it.
1091 You can input from a raw YUV420P file:
1094 avconv -i /tmp/test.yuv /tmp/out.avi
1097 test.yuv is a file containing raw YUV planar data. Each frame is composed
1098 of the Y plane followed by the U and V planes at half vertical and
1099 horizontal resolution.
1102 You can output to a raw YUV420P file:
1105 avconv -i mydivx.avi hugefile.yuv
1109 You can set several input files and output files:
1112 avconv -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
1115 Converts the audio file a.wav and the raw YUV video file a.yuv
1119 You can also do audio and video conversions at the same time:
1122 avconv -i /tmp/a.wav -ar 22050 /tmp/a.mp2
1125 Converts a.wav to MPEG audio at 22050 Hz sample rate.
1128 You can encode to several formats at the same time and define a
1129 mapping from input stream to output streams:
1132 avconv -i /tmp/a.wav -map 0:a -b 64k /tmp/a.mp2 -map 0:a -b 128k /tmp/b.mp2
1135 Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
1136 file:index' specifies which input stream is used for each output
1137 stream, in the order of the definition of output streams.
1140 You can transcode decrypted VOBs:
1143 avconv -i snatch_1.vob -f avi -c:v mpeg4 -b:v 800k -g 300 -bf 2 -c:a libmp3lame -b:a 128k snatch.avi
1146 This is a typical DVD ripping example; the input is a VOB file, the
1147 output an AVI file with MPEG-4 video and MP3 audio. Note that in this
1148 command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
1149 GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
1150 input video. Furthermore, the audio stream is MP3-encoded so you need
1151 to enable LAME support by passing @code{--enable-libmp3lame} to configure.
1152 The mapping is particularly useful for DVD transcoding
1153 to get the desired audio language.
1155 NOTE: To see the supported input formats, use @code{avconv -formats}.
1158 You can extract images from a video, or create a video from many images:
1160 For extracting images from a video:
1162 avconv -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
1165 This will extract one video frame per second from the video and will
1166 output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
1167 etc. Images will be rescaled to fit the new WxH values.
1169 If you want to extract just a limited number of frames, you can use the
1170 above command in combination with the @code{-frames:v} or @code{-t} option,
1171 or in combination with -ss to start extracting from a certain point in time.
1173 For creating a video from many images:
1175 avconv -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
1178 The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
1179 composed of three digits padded with zeroes to express the sequence
1180 number. It is the same syntax supported by the C printf function, but
1181 only formats accepting a normal integer are suitable.
1184 You can put many streams of the same type in the output:
1187 avconv -i test1.avi -i test2.avi -map 1:1 -map 1:0 -map 0:1 -map 0:0 -c copy -y test12.nut
1190 The resulting output file @file{test12.nut} will contain the first four streams
1191 from the input files in reverse order.
1194 To force CBR video output:
1196 avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
1200 The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
1201 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
1203 avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext
1210 @include decoders.texi
1211 @include encoders.texi
1212 @include demuxers.texi
1213 @include muxers.texi
1214 @include indevs.texi
1215 @include outdevs.texi
1216 @include protocols.texi
1217 @include bitstream_filters.texi
1218 @include filters.texi
1219 @include metadata.texi
1224 @settitle avconv video converter
1226 @c man begin SEEALSO
1227 avplay(1), avprobe(1) and the Libav HTML documentation
1230 @c man begin AUTHORS
1231 The Libav developers